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For a fully oriented molecule, the dipolar coupling for an 1 H-15 N amide group would be over 20 kHz, and a pair of protons separated by 5 Å would have up to ~1 kHz coupling. However the degree of alignment achieved by applying magnetic field is so low that the largest 1 H-15 N or 1 H-13 C dipolar couplings are <5 Hz. [19]
Magnetic dipole–dipole interaction, also called dipolar coupling, refers to the direct interaction between two magnetic dipoles. Roughly speaking, the magnetic field of a dipole goes as the inverse cube of the distance, and the force of its magnetic field on another dipole goes as the first derivative of the magnetic field. It follows that ...
Solid-state 900 MHz (21.1 T [1]) NMR spectrometer at the Canadian National Ultrahigh-field NMR Facility for Solids. Solid-state nuclear magnetic resonance (ssNMR) is a spectroscopy technique used to characterize atomic-level structure and dynamics in solid materials. ssNMR spectra are broader due to nuclear spin interactions which can be categorized as dipolar coupling, chemical shielding ...
The jet erosion test (JET), or jet index test, is a method used in geotechnical engineering to quantify the resistance of a soil to erosion. The test can be applied in-situ after preparing a field site, or it can be applied in a laboratory on either an intact or a remolded soil sample .
From the change in diameter of the hole over time, the rate of erosion can thus be plotted against applied hydraulic shear stress and fit to the following equation: [1] [4] = where E r is the rate of erosion over time, k d is the soil erodibility, and τ c is the critical shear stress for erosion.
This is called relaxation in the laboratory frame. Another technique, called relaxation in the rotating frame, is the relaxation of nuclear magnetization in the presence of the field B 0 together with a time-dependent magnetic field B 1. The field B 1 rotates in the plane perpendicular to B 0 at the Larmor frequency of the nuclei in the B 0.
The full form of the J-coupling interaction between spins 'I j and I k on the same molecule is: H = 2π I j · J jk · I k. where J jk is the J-coupling tensor, a real 3 × 3 matrix. It depends on molecular orientation, but in an isotropic liquid it reduces to a number, the so-called scalar coupling. In 1D NMR, the scalar coupling leads to ...
The three dipolar relaxation pathways contribute to differing extents to the spin-lattice relaxation depending a number of factors. A key one is that the balance between ω 2 , ω 1 and ω 0 depends crucially on molecular rotational correlation time , τ c {\displaystyle \tau _{c}} , the time it takes a molecule to rotate one radian.